Abstract
Charged Higgs bosons heavier than the top quark and decaying via H± →\r tb are searched for in proton-proton collisions measured with the ATLAS experiment at\r √s = 8 TeV corresponding to an integrated luminosity of 20.3 fb−1. The production of a\r charged Higgs boson in association with a top quark, gb → tH±, is explored in the mass\r range 200 to 600 GeV using multi-jet final states with one electron or muon. In order to\r separate the signal from the Standard Model background, analysis techniques combining\r several kinematic variables are employed. An excess of events above the backgroundonly\r hypothesis is observed across a wide mass range, amounting to up to 2.4 standard\r deviations. Upper limits are set on the gb → tH± production cross section times the\r branching fraction BR(H± → tb). Additionally, the complementary s-channel production,\r qq0 → H±, is investigated through a reinterpretation of W0 → tb searches in ATLAS. Final\r states with one electron or muon are relevant for H± masses from 0.4 to 2.0 TeV, whereas\r the all-hadronic final state covers the range 1.5 to 3.0 TeV. In these search channels, no\r significant excesses from the predictions of the Standard Model are observed, and upper\r limits are placed on the qq0 → H± production cross section times the branching fraction\r BR(H± → tb).